- 您现在的位置：买卖IC网 > PDF目录17413 > SP7662EB (Exar Corporation)EVAL BOARD FOR SP7662 PDF资料下载
参数资料
| 型号： | SP7662EB |
| 厂商： | Exar Corporation |
| 文件页数： | 13/19页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7662 |
| 标准包装： | 1 |
| 系列： | * |
S P 7 6 6 2
P o w e r b l o x T M
1 2 A 3 0 0 K H z S y n c h r o n o u s S t e p D o w n R e g u l a t o r
where:
f s = switching frequency
K R = ratio of the AC inductor ripple current to
the maximum output current
The peak-to-peak inductor ripple current is:
The copper loss in the inductor can be
calculated using the following equation:
where I L(RMS) is the RMS inductor current that
can be calculated as follows:
1 ? I PP ?
Once the required inductor value is selected,
the proper selection of core material is based
I L ( RMS ) ? I OUT ( MAX ) ? 1 ?
? ?
3 ? I OUT ( MAX ) ?
2
on peak inductor current and efficiency
requirements. The core must be large enough
not to saturate at the peak inductor current
and provide low core loss at the high switching
frequency. Low cost powdered-iron cores have
a gradual saturation characteristic but can
introduce considerable AC core loss, especially
when the inductor value is relatively low and
the ripple current is high. Ferrite materials,
although more expensive, have an abrupt
saturation characteristic with the inductance
dropping sharply when the peak design
current is exceeded. Nevertheless, they are
preferred at high switching frequencies
because they present very low core loss while
the designer is only required to prevent
saturation. In general, ferrite or
molypermalloy materials are a better choice
for all but the most cost sensitive applications.
O PTIMIZING E FFICIENCY
The power dissipated in the inductor is equal
to the sum of the core and copper losses. To
minimize copper losses, the winding resistance
needs to be minimized, but this usually comes
at the expense of a larger inductor. Core
losses have a more significant contribution at
low output current where the copper losses
are at a minimum, and can typically be
neglected at higher output currents where the
copper losses dominate. Core loss information
O UTPUT C APACITOR S ELECTION
The required ESR (Equivalent Series
Resistance) and capacitance drive the
selection of the type and quantity of the
output capacitors. The ESR must be small
enough that both the resistive voltage
deviation due to a step change in the load
current and the output ripple voltage do not
exceed the tolerance limits expected on the
output voltage. During an output load
transient, the output capacitor must supply all
the additional current demanded by the load
until the SP7662 adjusts the inductor current
to the new value.
In order to maintain V OUT , the capacitance
must be large enough so that the output
voltage is held up while the inductor current
ramps to the value corresponding to the new
load current. Additionally, the ESR in the
output capacitor causes a step in the output
voltage equal to the current. Because of the
fast transient response and inherent 100% to
0% duty cycle capability provided by the
SP7662 when exposed to output load
transients, the output capacitor is typically
chosen for ESR, not for capacitance value.
The ESR of the output capacitor, combined
with the inductor ripple current, is typically the
main contributor to output voltage ripple. The
maximum allowable ESR required to maintain
a specified output voltage ripple can be
calculated by:
is usually available from the magnetics
vendor. Proper inductor selection can affect
the resulting power supply efficiency by more
than 15%!
where:
R ESR ?
? V OUT
I PK ? PK
ΔV OUT = peak-to-peak output voltage ripple
? 2012 Exar Corporation
13/19
Rev. 2.1.0
相关PDF资料 |
PDF描述 |
|---|---|
| SP7655EB | EVAL BOARD FOR SP7655 |
| SP7653EB | EVAL BOARD FOR SP7653 |
| A9CAA-0804F | FLEX CABLE - AFG08A/AF08/AFG08T |
| LM2735YSDEVAL | BOARD EVAL LM2735 520KHZ 6LLP |
| A9AAT-1606F | FLEX CABLE - AFE16T/AF16/AFE16T |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7662ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7662ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 12A, 300kHz, Buck Regulator |
| SP7662ER-L | 功能描述:开关变换器、稳压器与控制器 Buck Regulator RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| SP7662ERL/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 12A, 300kHz, Buck Regulator |
| SP7662ER-L/TR | 功能描述:开关变换器、稳压器与控制器 WIDE INPUT VOLTAGE Range12A300KHz RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
发布紧急采购，3分钟左右您将得到回复。